Disaggregation apparatus for producing fine dispersions

ABSTRACT

Disaggregation apparatus for producing fine dispersions comprises a rotary disc and a stator disc having circular rings of teeth protruding into each other and arranged side-by-side with the rings of stator teeth disposed in alternate relation with the rings of rotor teeth, all the rings of teeth being concentric with each other. The space between the teeth comprises apertures identical in number and width for each tooth ring. The apertures both in the stator disc and in the rotor disc are rearwardly inclined relative to the direction of rotation, the differences between the angle included between the center line of the apertures of the stator and rotor discs and the radii from the axis of rotation decreasing in a radially outward direction. In other words, the apertures are progressively less rearwardly inclined in a radially outward direction.

[ June 11, 1974 DISAGGREGATION APPARATUS FOR PRODUCING FINE DISPERSIONSInventors: Tamas Apostol; Janos Barna; Alaios Egri; Zsigmond Kaplar;Tibor Majtenyi, all of Budapest, Hungary Banyaszati Kutato Intezet,Budapest, Hungary Filed: Apr. 18, 1972 App]. No.: 245,162

Assignee:

US. Cl 241/188 A, 24l/259.l, 241/261 Int. Cl. B02c 7/04 Field'of Search241/163, 261, 261.1, 261.2, 241/261.3, 188 R, 188 A, 55, 56, 250, 259.1,244

References Cited UNITED STATES PATENTS 4/1929 Michal 241/261 X 11/1932Gaiser 241/188 A X 3/1942 Ambrosem. 24l/26l.l X

12/1952 Scherer 241/261 X 1/1955 Rogers 241/56 X 12/1962 Aldred et a1241/56 X FOREIGN PATENTS OR APPLICATIONS 9/1920 Netherlands 241/261592,689 8/1925 France 241/188 A Primary Examiner-Granville Y. Custer,Jr. Assistant Examiner-Howard N. Goldberg Attorney, Agent, or Firm-Young& Thompson [57] ABSTRACT Disaggregation apparatus for producing finedispersions comprises a rotary disc and a stator disc having circularrings of teeth protruding into each other and arranged side-by-side withthe rings of stator teeth disposed in alternate relation with the ringsof rotor teeth, all the rings of teeth being concentric with each other.The space between the teeth comprises apertures identical in number andwidth for each tooth ring. The apertures both in the stator disc and inthe rotor disc are rearwardly inclined relative to the direction ofrotation, the differences between the angle included between the centerline of the apertures of the stator and rotor discs and the radii fromthe axis of rotation decreasing in a radially outward direction. Inother words, the apertures are progressively less rearwardly inclined ina radially outward direction.

1 Claim, 5 Drawing Figures PATENTEBJUN I I 974 SHEET 10F 2DISAGGREGATION APPARATUS FOR PRODUCING FINE DISPERSIONS This inventionconcerns a disaggregation apparatus for producing fine dispersionscontinuously while using substantially less power and in considerablyless time than known disaggregation apparatus.

In numerous industrial fields, e.g., food canning, various chemicalprocessing, organophilic clay manufacturing, water purifying, groundlevel and underground building, manufacture of fine ceramic materials,enamels and paints, hydraulic binders, building materials, plasticsfoams, etc., the attainable or attained degree of fineness is of greatimportance, because achieving an optimum degree of fineness enablesappreciable material consumption savings and a substantial improvementin the produced material quality to be made.

To reach the appropriate degree of fineness it was formerly usual toemploy a variety of wetting, comminuting, grinding and mixing processeswhich in more recent times have been replaced by techniques utilizingshear or impact; in turn, these have been replaced by selecting the mostappropriate disaggregation process for the material in questionemploying impact in combination with shearing. Disaggregation byimpacting while also shearing is more successful and more up-todate thanall other hitherto known processes. Nonetheless, it has not been adoptedto its merited extent; the reason is that it has not so far beenpossible to produce apparatus able to carry out the disaggregationprocesses on the appropriate scale and in the required quality overprolonged operating periods. Above all, with known disaggregationapparatus the economics of the results achieved have not beensatisfactory.

Known disaggregation apparatus do not allow material recirculationbecause, if recirculation is used, the

disaggregation process becomes discontinuous. Recirculation is, however,necessary because the structure of the material to be disaggregated(e.g., bentonite and similar materials) and dispersed must be brokendown in steps and because, to attain the appropriate shearing action, itis necessary to attain a suitable viscosity value which in many casescan be obtained only be recirculation.

The discontinuous recirculation techniques involved in knowndisaggregation apparatus entail the risk that individual materialportions are subjected to impacts more than others while being sheared;the product obtained is thus inhomogeneous.

In general, known disaggregation apparatus employ a rotary disc with arim provided with closely spaced teeth and a likewise densely toothedstationary counteracting disc in engagement with the teeth of the firstdisc. The material to be disaggregated and dispersed streams outwardlyfrom the interior of a vessel containing the disc. Its velocityincreases in the outer disaggregation parts and normally a great deal ofspace is available there for the material, whereby to lead to strongcavitation in the apparatus. As a result of cavitation, relativelylittle shearing action is exerted on the solid particles and the liquidparticles; the energy consumption, too, is high.

A further disadvantage of known disaggregation apparatus is that in themthe solid and liquid particles stream ina radial direction and asaresult of the ensuing friction lose a large part of their energy in theradially extending flow apertures. The lost energy reduces the amount ofenergy available for shearing.

A further defect of known disaggregation apparatus is that the shearingaction can be changed only by altering the speed of rotation of therotary disc. As a consequence of cavitation and the very largefrictional forces the power consumption is very high and the apparatussuffers relatively rapid wear and then can no longer be used.

An aim of the invention is to seek to provide a disaggregation apparatuswhich may operate by continuously recycling the material and in whichduring recycling each portion of the materials to be disaggregated anddispersed undergoes practically the same number of impact and shearingprocesses; in which the dispersion obtained displays a high degree offineness and is subtantially entirely homogeneous; in which nocavitation and no substantial frictional forces arise, in which theshearing action can be easily, quickly and continuously changed withoutaltering the operational r.p.m.; which is simple to operate, whichfunctions reliably over prolonged operating periods, and, which, whileusing relatively little power, will disaggregate and dis perse arelatively large quantity of material in a relatively short period oftime.

According to the present invention, there is provided disaggregationapparatus for producing fine dispersions, comprising a bladed rotor discand a vaned stator disc adapted to rotate relatively to one another andto produce impacts in and shearing of a material flowing there betweenso as to disaggregate and disperse the material, wherein the successiveannular sections of space available for the flowing material, taken atright angles to the direction of flow, are arranged to be substantiallyof the same size throughout by suitably shaping the blades, vanes andthe associated discs, there being respective apertures betweencircumferentially adjacent blades and vanes for ensuring an obliquematerial flow relative to the axis of rotation of the rotor, theapertures between adjacent blades of the rotor making an obtuse anglewith the direction of rotation of the rotor periphery, viewed in thedirection of flow of the material.

A preferred feature of the invention consists in that the shape of thedisc surface is, adjacent the blades or vanes, frusto-conical orcylindrical.

The rotor and/or the stator may be mounted in such a way that they canbe moved towards or away from each other.

Preferably, opposite blade/vane surfaces of interacting blades and vanesare cylindrical, in axial-flow arrangements. Opposite blade/vanesurfaces of interacting blade/vane rims may, however, to frusto-conical,in radial-flow arrangements.

The invention will now be described, by way of example only, withreference, to the accompanying diagrammatic drawings, in which:

FIG. 1 is a section of a preferred embodiment of the disaggregationapparatus according to the present invention;

FIG. 2 is a plan of the rotor and stator of the apparatus shown in FIG.1;

FIG. 3 is a partial, enlarged cross-section of a modified form of therotor shown in FIG. 1;

FIG. 4 shows another preferred embodiment of the invention, inbroken-away elevation in which the material to be disaggregated anddispersed flows through an annular space along the periphery of therotor and the disc in the axial direction, and

FIG. shows amoditied embodiment similar to that in FIG. 4 but differingin that here a plurality of alternate rotors and stator discs arearranged in series.

In the embodiment of the disaggregation apparatus according to FIGS. 1and 2 a rotor I is secured to and for rotation with a shaft 2 rotatablein a housing having parts 3, 5. The shaft 2 is rotatably mounted in abearing 4 located in the housing part 3 of the apparatus. A union member6 adapted to connect the apparatus to a pipe line or to introduce thematerial to be dispersed into the interior of thehousing parts 3, 5extends axially fromthe statorlike housing part 5 and is integrallyconstructed with the housing part 5, hereinafter referred to as stator5, or stator disc 5. The introduced material is discharged through aunion member 7.

Tooth or blade rings 8 made up of a row of blades are located on thesurface of the rotor 1 opposite the stator 5. The rings 8 are mutuallyspaced radially in such a way that tooth or blade rings 9 on the stator,having spaced apart stator vanes, can be inserted in between. Duringoperation the rings 8 thus rotate between the rings 9 in the directionof the arrow 10 shown in FIG. 2. The radially outermost part acting onthe material is a rotor blade ring.

The blades of the rings 8 are constructed so as to form apertures 11therebetween, the apertures being oblique with respect to the peripheryof the blade ring. The direction of the apertures makes an obtuse anglewith the direction of rotation of the periphery of the rotor, as viewedin the direction of material flow. Thus the side surfaces of theseapertures exert a similar action on the material as e.g., the rotatingimpeller wheel of a centrifugal pump, i.e., they can elevate the mate--rial to a certain height or convey it. The general shape of the rotorblades and stator vanes is cylindrical.

In use, the material to be disaggregated and dispersed flows between theteeth of the tooth ring 9 protruding from the stator disc 5, throughapertures 12 formed between adjacent stator vanes.

The above-described construction of the apertures 11, 12 and of therings 8 and 9 enables the transfer of the material flowing in-between;and, further, for rheological reasons, ensures that the flowing materialstreams through the apertures under small frictional forces, or that theparticles to be disaggregated are subjected to strong impactsrespectively. This mode of flow is very advantageous by comparison withthe hitherto employed purely radial mode of flow.

In the diagrammatically shown construction according to FIGS. 1 and 2,the wall of the housing part 3 is vertical with respect to the shaft 2,the top radial surface 13 of the rotor l, on the side of the blades, hasa somewhat curved cross-section, while the opposed inner surface of thestator disc 5 is substantially frustoconical. The surface 13 and theinner surface of the stator disc 5, and also the space between the rings8 and 9 filled with the material to be dispersed, are shaped anddimensioned in such a way that the annular crosssectional areas,considered at right angles to the material flow direction, areeverywhere of substantially the same size. This means that, viewedradially outwards from the axial line 14, the change in radius and hencethe change in length of the periphery is balanced out by changes in thewidth of the annular cross-section for every illustrated annularcross-section. Consequently,

the material entering through the union member 6, while spreading outbetween the surface 13 and the statordisc 5, flows in such a way thatdespite an increase in its velocity it fills the space between thesurface 13 and the stator disc 5 completely, i.e., substantially noflow-impairing cavitation can arise.

The embodiment according to FIG. 3 (wherein like parts have beenallotted like reference numbers) differs from that according to FIGS. 1and 2 only in what follows. Modified parts retain the same referencenumber but with the suffix a" added. The rotor blades 8a extending fromthe rotor 1 are not constructed cylindrically but frusto-conically (aretrapezoidal in section). Similarly shaped surfaces define the peripheryof the ringsmade up of the stator vanes 9a projecting from the wall ofthe stator disc 5a. A further difference is that the stator disc 5a maybe moved towards or away from the rotor 1. Of the many suitable ways ofachieving this, one example is shown: a screw connection 15. Thus thewidth of the gaps 16 between the side surface of the blades or vanes 8aand 9a may be varied, and hence the magnitude of the shearing action canbe changed without altering the angular speed of the rotor l In theembodiment of the disaggregation apparatus according to the inventionshown in FIG. 4 the material to be dispersed that has entered the unionmember 6 flows only through the outer annular part of a rotor 17 and astator 18. The rotor 17 has only a single blade ring whose blades fillthe entire width of the annular flow section. Opening or apertures. 19between the blades extend along the full height as the blades. Theapertures 19 make an angle with the direction of rotation of theperiphery of the rotor 17 equal to the angle between the apertures 11 onthe rotor l in the construction according to FIGS. 1 and 2. Theapertures 21 between the vanes 20 of the stator 18 are of the sameheight as the apertures 19. The direction of the apertures 21 is similarto that of the apertures 12 in the construction according to FIGS. 1 and2.

The construction according to FIG. 5 is essentially similar to thataccording to FIG. 4, with the difference that, here, a plurality ofalternate rotors and stators are arranged in axial-flow series. Thewidth of the gaps between the rotors l7 and stators 18, and hence alsothe shearing action, can also be constructed to be adjustable.

The principal advantages of the illustrated embodiments of thedisaggregation apparatus are the followmg:

Formation of detrimental cavitation effects are substantially preventedor reduced. The magnitude of the frictional forces arising during theflow is reduced by the particular construction of the apertures or gapsbetween the rotor blades and stator vanes. The result, based onmeasurements, is that the energy input required for the disaggregating,dispersing and shearing of a given amount of specified material is only27-29 percent of the energy required in known apparatus.

As a result of the substantial elimination or reduction of thecavitation, the shearing action is substantially increased and it ispossible to produce colloidal dispersions of materials which it has nothitherto been possible to disperse to a similar degree of fineness withthe hitherto known apparatus or which could be converted merely intocoarse-particle dispersions.

A further advantage consists in that as a result of the disclosedpump-like construction of the rotor and the stator the apparatus inaddition to a reduced power consumption and a greater shearing effectalso displays the property of working as a pump and is able to conveythe colloidal dispersion under a pressure of several atmospheres.

The shearing action can be controlled without discontinuities by virtueof the fact that the rotor and the stator, or a plurality of pairs ofsame, can be relatively axially displaced. The number of pairs of rotorsand stators can be selected in accordance with the requiredtechnological conditions. Incorporating the pairs in series can beperformed quickly with relatively little assembly work. in addition tobeing used for disaggregation and dispersion tasks the apparatus can beemployed also for pre-comminuting coarse-particle materials.

The invention is not limited to the illustrated preferred embodiments.For example the rotor and the stator may be constructed so that theyboth rotate, for example, in opposite angular senses; the continuousmatching of the flow cross-sections to the flow velocity may beperformed in an alternative manner to that disclosed above; the size ofthe angle that the flow apertures (blade/vane gaps) make with thedirection of rotation of the rotor periphery may be selected to bedependent on the quality and viscosity of the flowing material; and,when using series-connected rotor-stator pairs, the angles may bealtered to match the given technological requirements.

What we claim is:

l. Disaggregation apparatus for producing fine dispersions, comprising arotary disc and a stator disc each having a plurality of concentricteeth rings, the teeth rings of each of the rotor disc and stator discprotruding between the teeth rings of the other of the rotor disc andstator disc in alternate relationship, the space between the teethcomprising apertures identical in number and width for each tooth ring,the apertures both in the stator disc and in the rotor disc being ofbackward direction relative to the direction of rotation, there being adifference between the angle included between the center line of theapertures of the stator and rotor discs, and the radaii from the axis ofrotation said difference decreasing in a radially outward direction.

1. Disaggregation apparatus for producing fine dispersions, comprising a rotary disc and a stator disc each having a plurality of concentric teeth rings, the teeth rings of each of the rotor disc and stator disc protruding between the teeth rings of the other of the rotor disc and stator disc in alternate relationship, the space between the teeth comprising apertures identical in number and width for each tooth ring, the apertures both in the stator disc and in the rotor disc being of backward direction relative to the direction of rotation, there being a difference between the angle included between the center line of the apertures of the stator and rotor discs, and the radaii from the axis of rotation said difference decreasing in a radially outward direction. 